1. Field of the Invention
The present invention relates to a camera with a photoelectric focus detecting device and, more particularly, to a single lens reflex camera with a TTL type photoelectric focus detecting device having a photoelectric transducer means arranged to receive light from a picture-taking lens.
2. Description of the Prior Art
Various cameras with photoelectric focus detecting devices has been proposed and some of them have already been commercialized. The focus detecting device of the camera of such type is generally provided with a photoelectric transducer means.
In a camera, photoelectric conversion is necessary other than in focus detection. Photometry for the purpose of exposure control (exposure detection) is a good example. Therefore, with a camera of the type described above, it is very advantageous to use a common photoelectric transducer means for focus detection and exposure detection. Such concept has already been proposed in U.S. Pat. No. 4,047,187, Mashimo et al, SYSTEM FOR EXPOSURE MEASUREMENT AND/OR FOCUS DETECTION BY MEANS OF IMAGE SENSOR, patented on Sept. 6, 1977; corresponding to German DAS 25 64 230.
The proposal in this patent is an example of that the photoelectric transducer means in the focus detecting device is also used for an additional purpose. In a camera, however, photoelectric conversion is required for further various purposes. It is, therefore, advantageous to enable the photoelectric transducer means in the focus detecting device to be used for various purposes. This requirement is bocoming increasingly important.